Motor vehicle air suspension systems utilize compressed air operated leveling devices, as for example air springs and/or air controlled shock absorbers or a combination thereof, to provide ride and leveling control of the vehicle. Such air suspension systems utilize an air compressor to provide a source of compressed air to the air operated leveling devices. In a typical configuration, as for example described in any of U.S. Pat. Nos. 4,829,436, 5,465,209 and 6,698,778, the air compressor is selectively connected, by electronically controlled solenoid valves, to the air operated leveling devices, a compressed air reservoir, an air intake, and an air exhaust. Most air suspension systems operate in an “open state” in the sense the excess pressure within the system is vented to the atmosphere at the exhaust and the source air for the compressor is drawn from the atmosphere at the intake; however, at least one air suspension system (see above-cited U.S. Pat. No. 6,698,778) operates in a “closed state” in the sense that air is not exchanged with the atmosphere, wherein excess pressure is stored in an air reservoir and the source air for the compressor is either the air reservoir or the air springs.
Turning attention now to FIG. 1, an example of a prior art motor vehicle suspension system 10 is depicted, as generally also shown and described in aforementioned U.S. Pat. No. 4,829,436 to Kowalik et al, issued on May 9, 1989 and assigned to the assignee hereof, the disclosure of which is hereby incorporated herein by reference.
The motor vehicle air suspension system 10 includes four compressed air operated leveling devices 12 which may be air springs and/or air operated shock absorbers, or a combination thereof, a computer 14, a compressor/exhaust apparatus 16, an air drier 18, a pressure switch 20, a valve assembly 22, a plurality of air lines 24 and signal lines 26. The plurality of air lines 24 go to the four leveling devices 12 to provide pressurized air from the valve assembly 22. A road wheel 28 is associated with each leveling device 22. The computer 14 receives an ignition signal, vehicle speed signal and vehicle door disposition signal. The computer 14 controls the operation of each solenoid valve in the valve assembly 22. The computer 14 also receives input from sensors in three of the four road wheels 28 through the three signal lines 26. The compressor/exhaust apparatus 16 selectively sources or vents air through the air drier 18. A master air line 30 runs from the pressure switch 20 to the valve assembly 22 which controls compressed air communication between the compressor/exhaust apparatus 16 and the individual leveling devices 12 in response to signals from the computer 14. The pressure switch 20 also provides a signal to the computer 14 when the air pressure to any leveling device falls below 35 psi so that incremented pressure is automatically provided to that leveling device.
Problematically, the solenoid valves are external to the leveling devices. What remains needed in the art is an improved motor vehicle air suspension system wherein the solenoid valves are integrated into the leveling devices, whereby provided would be lower cost, weight, package size, and component complexity, as well as improved environmental protection and retained integrity of air compression even if the air line is untowardly damaged.